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New Scientist Live

When you eat beats what you eat in staying healthy

By Sara Reardon

Preventing obesity may be down to timing, in mice, at least. Mice allowed meals only within an 8-hour period were healthier than those that munched freely through the day, even when they consumed more fat.

A link between obesity and the time you eat meals makes sense, says Satchidananda Panda of the Salk Institute in La Jolla, California, as food choices generally get less healthy as the day progresses. Breakfast may include healthy fruits and grains, but late-night snacks are more likely to involve high-fat ice cream or high-calorie alcohol. Furthermore, research has shown that our internal clocks are closely tied to our metabolism; disrupting them can cause weight gain and diabetes.

Panda and colleagues fed two groups of mice a high-fat diet. One group could snack whenever they liked, the other could only eat during an 8-hour window. Both groups consumed the same number of calories each day. Two other groups were fed a healthy diet under the same conditions.

Three months later, the weight of mice on the all-day, high-fat diet had increased by 28 per cent. Their blood sugar levels had gone up – a risk factor for diabetes – and they also had liver damage. In contrast, mice eating a high-fat diet for only 8 hours a day stayed healthy and didn’t become obese. They also had better balance than mice on a healthy diet.

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Panda reckons the shortened feeding period gives metabolic systems longer to perform their function uninterrupted by a new influx of nutrients.